Power over data (PoD) technologies have become ubiquitous for supplying electric energy to distributed devices over conventional data communication links. Particularly, power over Ethernet (PoE) technologies are gaining widespread use in ad-hoc systems which pass electrical power along with data on Ethernet cabling. PoD and specifically PoE are very efficient solutions if both data and power connections are to be led in one cable, so that equipment supplied with PoD/PoE does not require separate cables for data links and power supply. Therefore, PoD/PoE technology offers great advantages for devices with modest power consumption and high and/or constant data throughput. Employing PoD/PoE technologies saves costs for cabling, allows for remote cycling of power supply and guarantees a high data throughput.
Several approaches for improving the flexibility and functional capabilities of PoD/PoE technologies have already been made. For example, document EP 2 819 343 A1 discloses a method for changing an operating mode of a processing unit of a network node which is connected to a combined data communication and power supply line in which changes of the supply voltage of the combined data communication and power supply line are monitored and an operation mode of the processing unit is set based on a determined change of the supply voltage. Document DE 10 2008 007 023 A1 discloses a method for the voltage supply of aircraft cabin modules, in particular of safety-relevant modules in an aircraft cabin by a combined transmission of data and a supply voltage wherein the level of the supply voltage may be varied.